Clinical Trails Network - Clinical Evaluation of Novel Products for Female Contraception: Pilot and Efficacy Study with PK The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) has a mission to develop safe and effective contraceptives for women, including obese women. Obesity is the number one public health issue facing the US population and is an independent risk factor for venous thromboembolism (VTE). Therefore, there is a public health need to develop effective contraception for obese woman that does not increase the risk of VTE. Products containing the synthetic estrogen, ethinyl estradiol, have been associated with a dose dependent increase in VTE. Products containing the natural hormone, estradiol, or progestin only products have the potential for a much lower risk of VTE. One example of such potentially safer products is a new contraceptive vaginal ring (CVR) that can deliver a continuous dose of Nestorone (Nes) and estradiol (E2). The Nes/E2 ring has the potential to provide effective long term contraception without the need for daily intervention. Examples of safer progestin-only methods are levonorgestrel formulations (patch or injection) or desogestrel (pill). In order to evaluate if new products could be effective for contraception, a clinical trial will be conducted in the NICHD Contraceptive Clinical Trials Network (CCTN). The proposed study will be conducted in women of reproductive age in order to evaluate contraceptive efficacy, pharmacokinetics, bleeding patterns, and the safety and side effects of this new contraceptive product. In the event of substantial product delay or failure, reprioritization may result in testing of a different product in the CDDB development pipeline. In such cases, the scope and objectives remain the same and the specifics of the technical requirements will be modified according to the latest approved protocol.